Pass arguments to pylint child process via a pipe.

This gets around command-line length limitations.

BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10654002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@143620 0039d316-1c4b-4281-b951-d872f2087c98

presubmit_canned_checks.py

@@ -653,11 +653,24 @@ def RunPylint(input_api, output_api, white_list=None, black_list=None,
   def run_lint(files):
     # We can't import pylint directly due to licensing issues, so we run
     # it in another process. Windows needs help running python files so we
-    # explicitly specify the interpreter to use.
+    # explicitly specify the interpreter to use. It also has limitations on
+    # the size of the command-line, so we pass arguments via a pipe.
     command = [input_api.python_executable,
-               input_api.os_path.join(_HERE, 'third_party', 'pylint.py')]
+               input_api.os_path.join(_HERE, 'third_party', 'pylint.py'),
+               '--args-on-stdin']
     try:
-      return input_api.subprocess.call(command + files + extra_args, env=env)
+      child = input_api.subprocess.Popen(command, env=env,
+          stdin=input_api.subprocess.PIPE)
+
+      # Dump the arguments to the child process via a pipe.
+      for filename in files:
+        child.stdin.write(filename + '\n')
+      for arg in extra_args:
+        child.stdin.write(arg + '\n')
+      child.stdin.close()
+
+      child.communicate()
+      return child.returncode
     except OSError:
       return 'Pylint failed!'
 

tests/presubmit_unittest.py

@@ -10,6 +10,7 @@
 import logging
 import os
 import StringIO
+import subprocess
 import sys
 import time
 
@@ -2143,9 +2144,18 @@ class CannedChecksUnittest(PresubmitTestsBase):
     input_api.os_walk('/foo').AndReturn([('/foo', [], ['file1.py'])])
     pylint = os.path.join(_ROOT, 'third_party', 'pylint.py')
     pylintrc = os.path.join(_ROOT, 'pylintrc')
-    input_api.subprocess.call(
-        ['pyyyyython', pylint, 'file1.py', '--rcfile=%s' % pylintrc],
-        env=mox.IgnoreArg())
+
+    # Create a mock Popen object, and set up its expectations.
+    child = self.mox.CreateMock(subprocess.Popen)
+    child.stdin = self.mox.CreateMock(file)
+    child.stdin.write('file1.py\n')
+    child.stdin.write('--rcfile=%s\n' % pylintrc)
+    child.stdin.close()
+    child.communicate()
+    child.returncode = 0
+
+    input_api.subprocess.Popen(['pyyyyython', pylint, '--args-on-stdin'],
+        env=mox.IgnoreArg(), stdin=subprocess.PIPE).AndReturn(child)
     self.mox.ReplayAll()
 
     results = presubmit_canned_checks.RunPylint(

third_party/pylint.py

@@ -13,7 +13,19 @@
 # 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 """ Copyright (c) 2002-2008 LOGILAB S.A. (Paris, FRANCE).
 http://www.logilab.fr/ -- mailto:contact@logilab.fr
+
+Copyright (c) 2012 The Chromium Authors. All rights reserved.
 """
 import sys
 from pylint import lint
-lint.Run(sys.argv[1:])
+
+args = sys.argv[1:]
+
+# Add support for a custom mode where arguments are fed line by line on
+# stdin. This allows us to get around command line length limitations.
+ARGS_ON_STDIN = '--args-on-stdin'
+if ARGS_ON_STDIN in args:
+  args = [arg for arg in args if arg != ARGS_ON_STDIN]
+  args.extend(arg.strip() for arg in sys.stdin)
+
+lint.Run(args)